As far as the Bible as our sole authority. My PERSONAL experience was this.
When I was an unsaved druggie, I managed to get my hands on a New Testament. I started at the beginning and read. I was facinated at what I read and as being raised as a roman catholic, I couldn't understand why there were so many things that contradicted what I learned in church. One of those things was that Jesus had brothers and sisters. I read it, I believed it. I didn't understand at the time, I was stupid and uneducated and didn't know all the "traditions" and "other baggage" that had to go along with the Word to make me a good Christian. I didn't know Greek, Aramic, Hebrew, etc, etc...
For me the answer is simple. If I was a lost sinner stranded on an island, shipwrecked, with no hope of escape, and all I had was one King James Bible, I believe there would be EVERYTHING I needed in that book to lead me to salvation, and an eternity with Jesus Christ.
No veneration of Mary, believing Jesus had brothers and sisters, what it said, I'd believe, just like when I read it from beginning to end with NO church affiliation, no pre-concieved doctrine, no understanding of what it "really" said in Greek, and no teaching from any slanted point of view. I found everything I needed in that book to get me excited about God, to want to meet him personally and to spend my eternity with Jesus.
Jesus said people would stumble over the "simplicity" of the gospel. Believing Mary was sinless, sexless, etc just doesn't help ME at all. And when I picked up that Bible for the very first time and read and understood how I was lost to God and to Jesus, believe me all I cared about at that moment was ME...
